The term 'close up' can be broken down into four crossword solutions: SEAL (4 letters), END (3 letters), FOLD (4 letters), and FORBID (6 letters). SEAL is a verb meaning to make something airtight or watertight by using a material such as wax, tar, or pitch. END is a verb meaning to bring something to an END or conclusion. FOLD is a verb meaning to bend or double over so that one part of it covers another. FORBID is a verb meaning to prohibit or prevent something from happening. Together, these four words describe the act of closing something up, either physically or metaphorically.